In military applications, reeling devices for aerial towed targets and the like are well known and are used to reel out and reel in a towed target from a moving aircraft at desired speeds. In the past, such reeling machines have utilized electric motors, turbine driven devices as well as other types of supplementary power devices and brakes to reel equipment in and out from an aircarft. More recently, the prior art has developed reeling machines powered by means of an air driven turbine which are preferable to other prior art devices in that they can take advantage of the available power produced by ram air energy impinging upon the device during aircraft flight.
Although a variety of prior art air turbine reeling machines have been developed, most of such prior art turbine reeling machines have had their turbine blades exposed or have utilized variably pitched turbine blades which are extremely expensive for the purposes of providing variable reeling speeds to the reeling equipment. Further, such prior art turbine powered reeling machine devices have typically suffered from the their inability to utilize the turbine output for both a power source for reeling in, as well as, a power dissipator paying out applications. Examples of such prior art turbine powered devices are shown in U.S. Pat. Nos. 2,760,777 issued to Cotton; 2,778,584 issued to Wilson; and, 2,892,599 issued to Baldwin, et al., all of which fail to use the turbine rotor of the reeling machine to provide for reeling in and reeling out applications of the reeling machine. In this regard, Cotton, Wilson and Bladwin all disclose fixed pitch turbine blade design concept with various means of throttling the air mass flow through the turbine in order to solely control the reel in rate not the reel out rate. Cotton controls reel or pay out rate by means of a motor applied friction brake, while Wilson and Baldwin both rely upon centrifugally applied friction brakes to control reel out rate or speed. The use of such friction brakes to provide torque to oppose target drag is undesirable since its generates significant heat and wear due to relatively large power dissipation requirements.
In recognizing the heat and wear problems due to such friction brake designs, a prior art device shown in Hopper, et al., U.S. Pat. No. 2,751,167 discloses a variable pitch turbine in which the blades of the turbine may be rotated to various attack angles to provide torque for reel in or provide opposing torque for reel out applications. However, such variable pitch turbine blade designs are extremely expensive, require constant operator monitoring of turbine speed and, hence, have not been widely utilized in the prior art.
Alternatively, Hopper proposes a fixed pitch turbine coupled to a reversing gear train to achieve the required reel in, reel out bi-directional operation. The complexity of a reversing gear train has prevented the design's wide spread use.
As such, there exists a substantial need in the art for an improved aerial tow target reeling machine which utilizes a turbine head design to take advantage of the impinging ram air force existing during aircraft flight and which allows bi-directional turbine rotational operation with a fixed turbine blade configuration so as to provide proper reeling out and reeling in speeds for the reeling machine without the heretofore requirement of supplemental frictional brakes, variable pitched turbine blades and/or reversing gear trains.